Hyperlink in Popup bringing up garbage url

I've configured a popup for PLSS townships to show a hyperlink for an ftp server with files organized by township.

When I click the link in the AGOL map viewer on a desktop browser (chrome) the link works fine. If I click the link while viewing the map in a web app the link results in a garbage url and fails. When I test this on an android tablet neither the map viewer not the web app work.

There is a specific set of HTML tags and protocols that can be used in the ArcGIS Online website. Any tags/protocols, like FTP that aren't listed on this document will be filtered out when the web map is saved which may explain the url that you are reporting.